The invention relates in general to thermostatic controls, and in particular to means for protecting a temperature-sensitive electronic module associated with a domestic range employing electric resistance heating elements.
The continuing advance of microelectronics has made possible the computerized control of domestic appliances such as programmable microwave cooking ovens, automatic dishwashers, domestic ranges and the like. The associated integrated circuit containing electronic module for accomplishing such computerized microelectric control, while continuing to decrease in cost, still constitutes a high cost component of the controlled appliance, and thus must be fully protected from damaging high temperature conditions.
The problem of module temperature control is especially acute in a microcomputer-controlled domestic range having a horizontal cooking platform providing a plurality of resistance wire surface heating elements and a pyrolytic type self-cleaning oven located below the platform, the oven including radiant heating elements also formed of resistance wire.
In such a range, the electronic control module is typically contained within a boxlike control unit extending upwardly from and across the back edge of the cooking platform. Where the range is located in a confined area, it may be possible to overheat the module-containing control unit during a high-temperature self-cleaning cycle of the oven and/or during improper usage of surface heating units in an unloaded condition (i.e., without a cooking utensil placed on the energized surface heating element).
To protect the electronic module from damage by high temperatures, means must be provided to limit to a tolerable level an over-temperature condition of the module caused by the energization of one or more of the heating elements. Such a temperature limiting means must be durable and very reliable, due to the relatively long life expectancy of domestic appliances. Also, such a means must be low in cost due to the competitive nature of the domestic appliance business.